BY Michelle Garcia

February 26 2013 12:47 PM ET

A group of 75 Republicans have signed a court brief telling the U.S. Supreme Court that marriage is a constitutional right for same-sex couples in America.

The brief is in reference to California's Proposition 8, which rescinded rights for same-sex couples to wed after the state Supreme Court legalized the practice in 2008, the New York Times reports.

The group includes former governors Christine Todd Whitman of New Jersey, Jon Huntsman of Utah, and William Weld of Massachusetts, as well as Hewlett-Packard CEO Meg Whitman (who supported Prop. 8 while running for governor of California, representatives Ileana Ros-Lehtinen of Florida and Richard Hanna of New York, and several George W. Bush administration staffers. Three major Republicans who have expressed their support for legalizing marriage equality, Colin Powell, Laura Bush, and Dick Cheyney, have not signed the brief. Still, more Republicans may sign onto the brief.

Ken Mehlman, the former chair of the Republican National Committee who came out as gay and now sits on the board of the American Foundation for Equal Rights said he had been working for months to gather the signatures.

"We are trying to say to the court that we are judicial and political conservatives, and it is consistent with our values and philosophy for you to overturn Proposition 8," he said in the Times.

Retired House Republican Deborah Pryce of Ohio explained her reason for signing the brief.

"Like a lot of the country, my views have evolved on this from the first day I set foot in Congress," she said. "I think it’s just the right thing, and I think it’s on solid legal footing, too."

The brief indirectly challenges the effort put forth by House Republicans who have taken on the task to defend the so-called Defense of Marriage Act in federal court cases after the Obama administration announced that it would no longer defend the law in court. DOMA will be argued before the Supreme Court along with the Proposition 8 case in March.

According to The Atlantic, the National Organization for Marriage announced Monday that it would "do everything in its power to defeat any Republican who votes in favor of same-sex marriage."

The Proposition 8 case will be argued by conservative attorney Theodore B. Olson, the solicitor general under President George W. Bush. He and his co-counsel on the case, David Boies, faced each other in the 2000 Supreme Court case of Bush v. Gore.